The main goal of this project is to study the effect of aging, stress and drugs on the blood pressure of spontaneously hypertensive rats. (1) Three oxindole derivatives of Uncarine A alkaloid have been synthesized and tested for an Uncarine-like antihypertensive and tranquilizing action. (2) A gas chromatographic-Mass Spectrometric assay procedure for simultaneous measurement of nanogram level of dopamine and its metabolite, 3-methoxytyramine in brain tissue has been developed. Results indicate that O-methylated rather than deaminated metabolite of dopamine is a better index for the measurement of neuronal activity in the central dopaminergic systems. The striatal level of 3-methoxytyramine and behavioral activity in the spontaneously hypertensive rats is higher than that in the normotensive rats after administration of amphetamine or stress. (3) A 30 min immobilization induced an irreversible cardiovascular failure in the aged Wistar and Fischer-344 rats while it produced little effect on 12 month old rats.